1. Field of Invention
The present invention relates to a valve; and more particularly relates to a fluid release value, which may also be known as a pressure relief valve, a drain valve, or a pressure equalization valve.
2. Description of Related Art
Currently, there exists many forms of relief valves which allow a fluid or gas to escape a line or pipe (referred to as “fluid” henceforth). Typically, these valves allow the release of the fluid once that fluid has reached a preset pressure threshold, or in some cases, a certain level of vacuum. Such valves often utilize diaphragms or spring-loaded valves to facilitate the release of a fluid above or below a certain pressure set-point. Typically springs are used for higher pressure release points and diaphragms for lower pressure release points. The very first versions of such relief valves used a weight to seal off the release path until a particular pressure had been achieved within the valve.
Other forms of relief valves only release the fluid upon manual activation by an operator via the use of a lever, knob, or other similar manual activation device. Still others have no spring, diaphragm, weight or other mechanical actuator and are single use, designed to relieve pressure by “blowing” off a component or rupturing a disc. There are also electronic versions of relief valves, e.g., which consist of electronically actuated solenoid valves controlled by a pressure transducer, pressure switch, or other similar activation sensor or device.
In addition to valves designed to release fluid (and therefore also relieve pressure) upon reaching a particular pressure set-point, there also exist many valves designed to drain a line, tank, or other system at low pressures. The simplest of these are manual valves using levers, knobs, or buttons to activate the release of the contained fluid. Some versions of drainage valves are designed to operate automatically, e.g., either using an electronically actuated solenoid valve or a spring loaded valve which works opposite the way the spring-loaded pressure relief valves function: Closing at a pre-set pressure and opening below that pressure threshold to allow the fluid to escape.
Some of the shortcomings of the above mentioned devices include the following:
The devices mentioned previously work well in certain situations but have several shortcomings which make them unsuitable for other applications, particularly the draining of fluid from a system that, during pumping, has low flow and pressure characteristics. Such a situation, which highlights how these existing valve forms can be unsuitable, is the case where a pump is positioned inside of a vertical well. When the time comes to retrieve the pump from the well, the fluid that remains inside of the pipe or hose can add significant weight to be overcome during the retrieval process. This additional weight is especially significant if the retrieval is being undertaken manually. In such a situation it would be advantageous to first drain the fluid out of the pipe or hose, thereby lessening the weight to be lifted and making the retrieval process less physically demanding.
In such a case it is desirable for the valve to only release the fluid once the pump has stopped. Valves which open based upon reaching a high level set-pressure will not work because, if they were set at such a pressure to relieve the fluid at rest, than they would also allow significant volumes of fluid to leak out during normal operation, which is inefficient and wasteful.
Valves which open at a low set-pressure will only work, e.g., if during normal operation of the pump, the pressure developed at the valve location is significantly higher than the pressure at the same location when the pump has stopped operation. With applications such as drip irrigation that produce high levels of backpressure this may be the case but with others, such as flood irrigation, it is unlikely to develop much of a pressure difference. In the flood irrigation example, where there is not a large pressure difference, a valve designed to be forced closed due to the working pressure will not be able to open once the pump has stopped. The reason behind this is because, once the valve seals the fluid release path, there is now an additional force (equal to the pressure difference between the interior of the valve and the exterior well water multiplied by the sealed off area) that is keeping the valve closed. An additional problem with trying to use a low set-pressure valve is that the pressure developed at the valve location will not be constant in many cases as it is dependent on the depth of the well and several other factors. This complicates the approach of trying to use a diaphragm or spring-loaded valve for such situations because the opening force provided by these will remain constant and will not self-adjust to compensate for changes in depth.
Manually and electronically operated valves will allow the column of fluid to be relieved from the hose or pipe when so desired and be independent of pressure and depth, but these systems add additional complexity and cost due to the need for components such as mechanical actuators or electronic connections and solenoids. Also, the ideal spot for full fluid drainage is at the base of the pumped column of fluid. This is typically at the bottom of a well, which makes it a harsh environment to seal electronics in the case of solenoid valves or would require lengthy mechanical actuators in the case of a manually operated valve.
In view of the aforementioned, there is a need in the industry for a better fluid relief valve, e.g., especially for applications related to well style installations.